Extraction,Purification,and Antioxidant Activities Of Flavonids From Plantago Species

Plantain(Plantaginaceae)is a traditional Chinese herbs.Three species(Plantago asiatica L.,P.major L.,and P.depressa Willd)of which are mainly used for medicine,and some mixed and shared species also used for medicine in the market and clinical applications.In this study,three origin plants of Plantago were selected for study.Comparing the differences of flavonoid content and antioxidative activity among the three species of Plantago,and accumulating data for promoting the comprehensive development of Plantago and effective utilization of resources,and providing certain basis for the development and industrial production of Plantago flavonoids.The main results are as follows:1.Ethanol extraction was used to extract the total flavonoids from three plantain species.The results of flavonoid yields were used to examine the effects of single factor such as extraction temperature,extraction time,solid-liquid ratio,and ethanol concentration.The conditions were showed that the ethanol concentration was 60%,the liquid-to-feed ratio was 15 mL/g,the extraction time was 100 min,and the extraction temperature was 50°C is the best extraction of total flavonoids from plantain.The total flavonoids of three species were extracted with the above conditions.The total flavonoids of Plantago asiatica L.was 3.41%,the yield of P.depressa Willd flavonoids was 0.30%,and the yield of P.major L.flavonoids was 0.90%.2.Ultrasonic extraction of flavonoids from P.asiatica showed that the optimal extraction coditions were determined as follows: liquid-solid ratio was 20(mL/g),ultrasonic time was 80 min,ultrasonic power was 210 W,the yield of total flavonoids of P.asiatica L.,P.major L.and P.depressa Willd were 5.0389%,2.8567% and 1.22%,respectively.Compared with hot water extraction,the yield of total flavonoids of P.asiatica L.increased by 0.47 times;the yield of total flavonoids of P.major L.increased by 2.18 times;the yield of total flavonoids of P.depressa Willd increased by 3.06 times.Ultrasonic extraction can effectively improve the extraction of flavonoids.3.The macroporous resins were used to purify the crude flavonoids of the three plantains.S-8 was selected from 7 kinds of macroporous resins to isolate and purify the flavonoids.The optimum conditions of purification of total flavonoids from P.asiatica L.were determined by experiment of macroporous resin,and the optimum conditions were sample pH value 4,concentration 4.8 mg/mL,eluent concentration 80% ethanol,eluent rate 2.0 mL/min and the volume of eluent 120 mL(6BV).Under this condition,the content of total flavonoids in P.asiatica L.was 36.65%,that of P.major L.was 36.65%,and that of P.depressa Willd was 36.65%.Compared with before purification,the content of total flavonoids of P.asiatica L.increased by 16.03%;that of P.major L.increased by 11.83%;that of P.depressa Willd increased by 5.01%.4.In vitro antioxidant activity of crude flavonoids and purified flavonoids from plantain showed that both before and after purification,the strongest effect of reducing ability and hydroxyl radical scavenging was P.major L.,the weakest was P.depressa Willd;flavonoids of P.asiatica L.revealed the strongest DPPH radical scavenging of activity,flavonoids of P.depressa Willd was weakest.According to the results of antibacterial test,the antibacterial effect of purified flavonoids was better than that of unpurified ones.In all,the antibacterial effect of the P.asiatica L.was the best and that of P.depressa Willd was weakest.It shows that the use of macroporous resin to purify flavonoids from P.asiatica has a certain effect,but with the development of separation and purification technology,there is still a need to explore better methods to improve its purification rate.5.Six common flavonoids were used as controls.The three kinds of purified flavonoids were detected by liquid chromatography.The results showed that the purified flavonoids from P.asiatica L.contain luteoloside;P.major L.scavenged flavonoids contain luteoloside,apiin,luteolin and apigenin,with higher contents of luteoloside,luteolin and apiin;The purified flavonoids of P.depressa Willd contained luteoloside,luteolin and apigenin.The contents of luteolin andluteoloside were high.